Conventionally, rotary fluid machineries have been known which include a fixed member and a movable member forming a fluid chamber together with the fixed member.
For example, a rotary fluid machinery disclosed in Japanese Unexamined Patent Application Publication 2005-330962 is so configured that a cylinder (a movable member) including an annular cylinder chamber, and an annular piston (a fixed member) arranged in the cylinder chamber are in relative revolution. In this rotary fluid machinery, the annular cylinder chamber is formed between an inside cylinder and an outside cylinder forming the cylinder. This cylinder chamber is defined into inside and outside cylinder chambers by the annular piston. Further, the outside and inside cylinder chambers are defined by a blade provided at the cylinder into a high pressure chamber and a low pressure chamber. The blade is fitted in a blade groove of a swing bush (a movable member support part) swingably supported by the annular piston. The cylinder thus supported by the blade and the swing bush moves back and forth relative to the swing bush while swinging about the swing bush in its revolution.
In the fluid machinery, when the cylinder is in the revolution relative to the annular piston, fluid is sucked to the low pressure chambers in the cylinder chambers, is compressed, and is then discharged from the high pressure chambers.